How to Test Your Keyboard
- Click Start Test.
- Press each key you want to check once.
- Check key responses, simultaneous presses, and possible chattering.
Use this keyboard checker to see which keys respond, how many keys register at once, and whether a single press may be producing duplicate input.
Unresponsive keys, unexpected mouse double-clicks, and drifting controller sticks can interrupt work and games. Device Checker is a free online tool for testing keyboards, mice, and gamepads, with no software installation or complicated setup.
Use it on Windows, macOS, or Linux to check a new gaming device, investigate wear on an older one, or inspect used hardware.
How to Check for Chattering and Double Input
Both the keyboard and mouse tests can flag possible duplicate input. The tool measures the time between releasing a key or button and pressing the same one again. Intervals below your selected chattering threshold increase the warning count and trigger an alert.
Keyboard Chattering Test
Click Start Test and press each key once. If a repeated press falls below the threshold, the Chattering Warn count increases, and the key name and interval appear in the alert and Input Log. Automatic repeats from holding a key down are excluded. This can help you check linear, tactile, or clicky mechanical keyboard switches.
Mouse Chattering and Double-Click Test
Open Mouse Test and slowly click each button once at a time inside the TEST AREA. If a repeated press falls below the threshold, the Chattering count increases, and the button number and interval appear in the alert and Input Log. Button 0 is left, Button 1 is middle, and Button 2 is right. Use this to investigate single clicks registering twice or drags releasing unexpectedly.
Choosing a Chattering Threshold
The default is 40ms. Choose 20ms to count only very short intervals, or 80ms to include a wider range. At 80ms, intentional rapid presses are more likely to count, so press or click slowly, once at a time. The threshold is a guide, not proof of a fault. Check whether the same key or button triggers warnings repeatedly.
Keyboard Layouts and Simultaneous Key Presses
The diagram shows a full-size keyboard. On a tenkeyless or 60% keyboard, check only the keys your keyboard has.
Switch Between US (ANSI) and Japanese (JIS) Layouts
Use the layout dropdown to switch between US and JIS diagrams. The JIS layout includes Japanese input keys such as Hankaku/Zenkaku, Convert, and NonConvert. The diagrams are simplified for checking input; key shapes may differ from your physical keyboard.
N-Key Rollover and Simultaneous Input
Hold down several keys to see whether they all register at the same time. This is useful for checking combinations around WASD or other keys used in action and rhythm games.
Mouse Test: Tracking and Button Responses
Test left and right clicks, scrolling, possible click chattering, sensor tracking, and extra mouse buttons.
Cursor Trail
Move your mouse inside the TEST AREA to draw a neon trail. Unexpected jumps may point to dirt on the sensor, a sensor problem, or a mouse pad issue. Try both slow and fast movements to check tracking.
Estimated Polling Rate (Hz)
The tool estimates your mouse polling rate from browser movement events and shows the current and maximum event rates. Browsers may combine movement events, so a mouse set to 1000Hz or higher may show a lower reading. Check your mouse software for its configured polling rate.
Extra Buttons and Scrolling
In addition to the usual three buttons, you can check side buttons such as Back and Forward. Button numbers appear in the Input Log to help check driver mappings. The scroll counter can help reveal unexpected direction changes from a worn wheel encoder.
Gamepad Test: Checking Stick Drift
Connect a controller, such as an Xbox controller, DualShock, DualSense, or Switch Pro Controller, and press a button to let the browser detect it.
Stick Drift
Stick input appears as a moving dot on a circular graph. If the dot stays off-center or shakes while you are not touching the stick, it may indicate stick drift. Small offsets can show WARN in the Drift field. A warning appears when a stick remains nearly still more than 10% away from center for at least three seconds. Release the stick before interpreting the warning.
Analog Triggers and Vibration
L2/R2 trigger readings range from 0.00 to 1.00 so you can check gradual presses, such as throttle and brake input. Click Test Vibration to check the controller's vibration motors. Vibration support depends on your browser and controller.
Troubleshooting Your Hardware
If a device behaves unexpectedly, check whether the cause is the hardware, computer settings, or drivers.
- Only certain keys fail: Dust or a worn contact may be the cause. Try cleaning the keyboard with compressed air.
- The cursor jumps: Check for dirt on the sensor and try another mouse pad.
- The gamepad is not detected: Try another USB port or cable, then press a controller button to activate browser input.
Frequently Asked Questions
How do I test my keyboard keys?
Click Start Test, then press each key once. Recognized keys change color on the layout. You can also see the last key, event.code, the number of keys held down, and the number of keys checked.
What is keyboard chattering?
Chattering is when a single key press registers multiple times in quick succession. This tool measures the interval between releasing a key and pressing it again to flag possible chattering.
Does an interval under 40ms mean my device is faulty?
No. The default 40ms threshold flags possible chattering; it does not confirm a hardware fault. Deliberate rapid presses, your browser, and your operating system can affect the result. Test several times.
How do I check for mouse chattering?
Open the Mouse Test tab and slowly click each button once at a time inside the TEST AREA. If the interval between releasing a button and pressing the same button again is below the threshold, the Chattering count increases and the button number and interval appear.
Does a single click registering as a double-click mean my mouse is faulty?
A worn switch may cause chattering, but this tool alone cannot confirm a fault. If it happens repeatedly even when you click slowly, try another USB port or computer.
Does holding down a key count as chattering?
No. This tool excludes automatic key repeats marked with event.repeat from the chattering warning count.
Are unresponsive Eisu, Kana, or Fn keys on a JIS keyboard faulty?
Not necessarily. Some special keys are handled by the browser or operating system and may not be available to a web page.
Are my keystrokes sent to a server?
No. Keystrokes are processed in your browser. Your input history is not sent to or stored on an external server.
Can I test on a phone?
You can open the page on a phone, but you need a physical keyboard to test key responses and chattering. Connect an external keyboard to use the keyboard test.
Why is my gamepad not responding?
Many browsers do not expose a connected controller until you press one of its buttons. After connecting, press a button such as A. Try a current version of Chrome or Edge if the controller is still not detected.
